实战演示jvm常见各种OOM异常

不念不忘少年蓝@ 2022-02-17 13:11 243阅读 0赞

jvm常见的oom异常，可以大致分为以下四种情况：

1.  堆内存溢出，堆上对象分配空间不足。
2.  栈内存溢出，栈内存问题有stackoverflowerror与outofmemoryerror两类，实际演示中stackoverflowerror比outofmemory更容易出现。
3.  常量内存溢出
4.  直接内存溢出

这四种方式在eclipse中编码，很容易复现，下面来介绍如何复现这四类异常。我们通过四个类分别模拟一种异常。如下图所示：

![2019041917083642.png][]

堆内存：HeapOOM.java

package com.xxx.oom;
    
    import java.util.ArrayList;
    import java.util.List;
    
    public class HeapOOM {
    	static class OOMObject{}
    
    	public static void main(String[] args) {
    		System.out.println("heapoom start.");
    		List<OOMObject> list = new ArrayList<HeapOOM.OOMObject>();
    		int count = 0;
    		while(true){
    			list.add(new OOMObject());
    			System.out.println("count : "+(++count));
    		}
    	}
    
    }

运行时虚拟机参数设置：-Dfile.encoding=UTF-8 -verbose:gc -Xms20m -Xmx20m -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=E:\\oomlog -XX:SurvivorRatio=8

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70][]

运行结果如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 1][]

栈内存：StackOOM.java

package com.xxx.oom;
    
    public class StackOOM {
    	
    	private int stackDep = 1;
    	
    	public void stackLeak(){
    		stackDep++;
    		stackLeak();
    	}
    
    	public static void main(String[] args) {
    		
    		StackOOM oom = new StackOOM();
    		
    		try{
    			oom.stackLeak();		
    		}catch(Throwable e){
    			System.out.println("栈深度: " + oom.stackDep);
    			e.printStackTrace();
    		}
    
    	}
    
    }

运行时虚拟机参数设置：-verbose:gc -Xms10M -Xmx10M -Xss128k -XX:+PrintGCDetails

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 2][]

运行结果如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 3][]

这里需要说明的是，我们的控制台输出错误信息里面显示的是stackoverflowerror，而不是outofmemoryerror，这个在前面提到过，stackoverflowerror比outofmemoryerror更容易出现。

常量：ConstantOOM.java

package com.xxx.oom;
    
    import java.util.ArrayList;
    import java.util.List;
    
    public class ConstantOOM {
    
    	public static void main(String[] args) {
    		try {
    			List<String> list = new ArrayList<String>();
    			int item = 0;
    			while(true){
    				list.add(String.valueOf(item++).intern());
    			}
    		} catch (Exception e) {
    			e.printStackTrace();
    			throw e;
    		}
    	}
    
    }

运行时虚拟机参数设置：-verbose:gc -Xms10M -Xmx10M -Xss128k -XX:+PrintGCDetails

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 4][]

运行结果如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 5][]

直接内存：DirectMemoryOOM.java

package com.xxx.oom;
    
    import java.nio.ByteBuffer;
    
    public class DirectMemoryOOM {
    	private static final int ONE_MB = 1024*1024*1024;
    	private static int count = 1;
    	public static void main(String[] args) {
    		try {
    			while(true){
    				ByteBuffer buffer = ByteBuffer.allocateDirect(ONE_MB);
    				count++;
    			}
    		} catch (Exception e) {
    			System.out.println("exception occur,instance count : "+count);
    			e.printStackTrace();
    		}
    	}
    }

运行时虚拟机参数设置：-verbose:gc -Xms10M -Xmx10M -XX:MaxDirectMemorySize=5M -Xss128k -XX:+PrintGCDetails

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 6][]

运行结果如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 7][]

以上通过代码与打印信息很直观的给我们展示了四类OOM异常，以及出现异常时的打印信息。方便我们了解这四类异常。

[2019041917083642.png]: /images/20220217/9801e4493bbb4045acaca25afa371120.png
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 2]: /images/20220217/8ba4af4dad8041568db5f12c979bf081.png
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70 7]: /images/20220217/96c26df5ca1b48358da1b92e563505c5.png